This specification relates to language processing systems.
The Internet provides access to a wide variety of resources for different resource properties. Such resource properties may include different websites, and/or different corpora that respectively provide video resources, image resources, web page resources, flight schedule resources, map resources, etc. Resources and services for each resource property are generally provided by servers or server systems. The resources and services are accessed through uniform resource identifiers (URIs) such as uniform resource locators (URLs).
One resource property that can be used to search the corpora is a search system web site. A search system crawls the Internet and indexes the resources and services in an index (or a set of indexes) for use in searching. A search system can search the resources using different search algorithms, where each algorithm designed for a specific corpus. Additionally, some search systems are configured to perform specific operations for some queries in addition to searching an index for the query. For example, the query “SF to ATL” may provide web pages that are responsive to the query, but may also provide a list of flights from San Francisco to Atlanta. The latter information may be gathered by accessing a service for a flight corpus in response to the query, and thus the user need not navigate to a flight database website and manually query for flights from San Francisco to Atlanta.
Providers of information are striving to provide users with access to this information in an intuitive, fluid manner. One way of providing such access is by speech recognition. Speech recognition and speech processing systems are prevalent in many consumer electronic devices. Many of these electronic devices now utilize speech command processing techniques to invoke and perform particular operations. For example, a user device, such as a smart phone, can process speech commands to perform specified operations that include searching the web, requesting a map, booking flights, and so on. Each of these operations may be carried out by different services on different corpora.
Often users will provide a clear indication of the type of information they need, and a search system can process the information accordingly. Such indications may be from queries that provide a clear expression of the user's informational needs. An example is the query [Map San Francisco to Atlanta]. However, sometimes users may not provide queries that clearly describe an informational need, or a search system may not have yet learned that a particular query should be used to invoke a particular operation. An example of such a query is [route me from San Francisco to Atlanta].